Method for reducing structural damage to the surface of monocrystalline aluminium-nitride substrates, and monocrystalline aluminium-nitride substrates that can be produced by a method of this type

Abstract

The present invention relates to a method for reducing structural damage to the surface of monocrystalline aluminium-nitride substrates, according to which the substrate undergoes thermal treatment in a crucible in an autoclave, during which treatment the aluminum-nitride substrate is sublimated in the damaged regions of the surface of the substrate and is removed. The method is used to prepare the surface of monocrystalline aluminium-nitride (AlN), in particular the aim of the invention is to eliminate, or at least significantly reduce near-surface structural damage to the monocrystalline material caused by mechanical processing. The invention also relates to aluminium-nitride substrates that are treated in this way.

1 - 12 . (canceled) 
     
     
         13 . A method for preparing the surface of a monocrystalline aluminium-nitride substrate, the method comprising heating the substrate undergoes in a crucible in an autoclave, which treatment results in a sublimation and removal of the aluminium nitride in damaged regions on the surface, wherein the heat treatment is carried out at a temperature of at least 2000° C. and in an atmosphere at an oxygen partial pressure of at most 10 −4  mbar. 
     
     
         14 . The method according to  claim 13 , wherein the heat treatment is carried out at a temperature of from 2000 to 2350° C. 
     
     
         15 . The method according to  claim 13 , wherein the heat treatment is carried out under vacuum at 1 mbar to 10 −4  mbar or in a protective gas atmosphere at 1 mbar to 1.5×10 3  mbar, wherein nitrogen, argon, helium or a combination thereof is selected as the protective gas. 
     
     
         16 . The method according to  claim 13 , wherein, during the heat treatment, the temperature gradient is at least 5° C./cm and the temperature gradient is perpendicular to the substrate surface. 
     
     
         17 . The method according to  claim 13 , wherein, during the heat treatment, the temperature gradient is at most 1° C./cm and the temperature gradient is parallel to the substrate surface in order to allow for lateral homogeneous material removal. 
     
     
         18 . The method according to  claim 13 , wherein, during the heat treatment, the temperature gradient is at least 1° C./cm and is parallel to the substrate surface, in order to set laterally inhomogeneous material removal for producing tilting of the surface normal relative to the <0001> crystal axis. 
     
     
         19 . The method according to  claim 13 , wherein a nitrogen-polar surface of aluminium nitride is removed from the substrate in a specific manner at an orientation of +/−5° relative to the <0001> crystal axis. 
     
     
         20 . The method according to  claim 13 , wherein the atmosphere comprises carbon. 
     
     
         21 . The method according to  claim 13 , wherein the crucible comprises tantalum carbide, from which carbon is released during the heat treatment. 
     
     
         22 . The method according to  claim 13 , wherein damage caused by pretreatment of the substrate is removed by a sawing process, a grinding process, a polishing process, or a combination thereof. 
     
     
         23 . The method according to  claim 13 , which includes removing the damage below the surface of the substrate. 
     
     
         24 . The method according to  claim 13 , which includes removing the damage in the rim region and/or to the edges of the substrate. 
     
     
         25 . A method of producing monocrystalline aluminium-nitride substrate, the method comprising heating an aluminium-nitride substrate in a crucible in an autoclave, which treatment results in a sublimation and removal of the aluminium nitride in damaged regions on the surface, wherein the heat treatment is carried out at a temperature of at least 2000° C. and in an atmosphere at an oxygen partial pressure of at most 10 −4  mbar.